The U.S. Geological Survey says the magnitude-3.2 tremor struck 5 miles south of the city of Napa just before 2 a.m. Sunday.

Thomas Brocher, director of USGS’ Earthquake Science Center, says it wasn’t the strongest aftershock to rumble the region since the main quake a week ago caused as much as $1 billion in damage and multiple injuries.

A magnitude-3.9 aftershock centered 8 miles south of Napa hit early Tuesday morning.

The USGS says there have been more than 70 aftershocks recorded since last Sunday’s earthquake.